The invention concerns a weir construction comprising a weir gate which is tiltable around an axis suspended in a canal section above the bottom thereof, whereby said axis is situated between. and at a distance from, the lower and the upper edge of the weir gate closer to the lower edge of the weir gate than to the upper edge thereof. which weir gate cooperates with control means for opening resp. cloging thereof by rotation around said axis.
Such weir constructions are generally known, e.g. from Dutch patent application NL-A-8702118. This type of weir construction comprises a weir gate allowing the water to flow both over and under the gate when it is opened. The weir gate is opened under the influence of the water pressure, as well as of control means such as a floating counter weight which is connected to the weir gate.
In its closed position, the weir gate lower edge should provide a seal with respect to the bottom of the canal section. However, this sealing action may be impaired by obstacles transported by the stream, such as sand, stones or dirt such as wood or water plants. In case these obstacles get stuck between the weir gate and the bottom of the canal section, the sealing action between weir gate lower edge and bottom is lost.